The thermal shock of receiving a cold substance on the body is a well known experience to everyone. Various home methods have been devised to warm bottles and containers before application of substances therein to humans or animals. In many cases, it is acceptable to warm the entire container each time an application is made if the substances therein are heat stable. In some cases, however, such repetitive warming can lead to degradation of the substance. For example, eye ointments are frequently comprised of a solidified mineral oil including petroleum and mineral oils along with chlorbutinol or paraben as a bacterial static agent in such combination that the ointment is a gel at ambient room temperature (e.g. 70.degree. F.) and a liquid at body temperature (98.6.degree. F.). Such ointments are advantageous in that almost any medication can be incorporated therein. In particular, medications may be ground into a fine almost colloidal size particle for suspension throughout the ointment, or aqueous solutions may be mixed with the ointment to form an emulsified water and oil suspension. In any case, repeated heating of either mixture would undoubtedly cause the colloidal particles or emulsified suspensions to separate from or congregate within the dependent portion of the mixture. Application of such mixture could then become unhelpful or dangerous because of uneven concentrations.
Continuing with the example of the gel-type eye ointment, such ointment is advantageous since the specific heat of the ointment does not cause abrupt thermal discomfort when the ointment is applied to an aye. The problem, however, is that a ribbon of the ointment must be squeezed from a tube and it is next to impossible to squeeze one drop or any other measured quantity. Frequently, an excessive amount is applied resulting in blurred vision because of the excess or resulting in some excess being squeezed out between the lids of the eye onto the surrounding skin and causing messy cosmetic problems, etc.
There have been attempts to design apparatus to preheat unit dose medications before application. For example U.S. Pat. No. 3,934,585 shows in FIG. 10 heating coils for both the dispensing tube itself and the end of the dispensing tube. The coils are resistive and become hot so that heat is transferred by conduction through the dispensing tube to the substance therein. The apparatus is obviously limited in its usefulness for reasons as discussed above as well as the necessity to shield surrounding objects from the heated coils and the necessity to make good thermal contact between the heated coil and the end of the dispensing tube.